JPH0633777U - Rear wheel steering system such as truck - Google Patents

Abstract

(57) [Summary] (Modified) [Purpose] Improving steering stability by steering the rear wheels at high speeds in a truck, etc., in which a rigid rear axle housing is suspended on a chassis frame through a leaf spring device. In addition, by utilizing the hydraulic cylinder device for steering the rear wheels, the impact caused by the step on the road surface is alleviated, the riding comfort is improved, and the vibration noise is reduced. [Structure] Rear wheel steering is performed by rotating a rigid rear axle housing, which supports rear wheels 18 at both ends in the vehicle width direction, around a ball joint arranged on the center line in the vehicle longitudinal direction. The steering of the rear wheels is performed by the front wheels 1
22 is performed by a pair of hydraulic cylinder devices 76, one of which expands and the other of which contracts, and when passing through a step on the road surface, a longitudinal acceleration or a vibration velocity acting on the vehicle body is applied. The impact is reduced by applying it to the vehicle body by the hydraulic actuator device 92 interposed between the chassis frame 10 and the rear axle housing.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a rear wheel steering device for a truck or the like.

[0002]

[Prior art]

 Conventionally, in a truck or the like in which the rear wheels are supported at both ends in the vehicle width direction of a rigid rear axle housing, and the rear axle housing is suspended by a chassis frame via a leaf spring device, the front wheels are steered at high speed. In order to improve steering stability, the rear axle housing itself is rotated in a small angle in-phase around the center of rotation arranged on the centerline in the longitudinal direction of the vehicle body. Rotary steering systems and devices have been proposed.

On the other hand, when a truck or the like equipped with the rear wheel steering device passes through a step or a joint on the road surface, an impact in the front-rear direction of the vehicle body is applied from the tire to the chassis frame, cab, and luggage box through the rear axle housing. As a result, there is a problem that riding comfort is deteriorated and vibration and noise are increased.

[0004]

[Problems to be solved by the device]

 The present invention improves steering stability by steering the rear wheels according to the steered steering of the front wheels during high-speed driving, and also mitigates the impact in the front-rear direction of the vehicle body that occurs when passing road steps or seams. An object of the present invention is to provide a rear wheel steering device such as a truck that can improve riding comfort and reduce vibration and noise.

[0005]

[Means for Solving the Problems]

 The present invention was devised to achieve the above-mentioned object, and includes a chassis frame, a rear axle housing that supports rear wheels at both end portions in the vehicle width direction, and one end portion of the rear axle housing arranged along the longitudinal center line of the vehicle body. An upper radius rod pivotally attached to the center portion of the rear axle housing in the vehicle width direction and the other end pivotally attached to the chassis frame, and the vehicle speed is set between the chassis frame and the rear axle housing. At the above times, the hydraulic cylinder device for steering the rear wheels that steers the rear wheels according to the steered steering of the front wheels, the vibration acceleration or the vibration speed in the vehicle front-rear direction that acts when passing a step on the road surface, etc. Receiving the output signals of the device that detects the vibration and the device that detects the vibration acceleration or the vibration velocity, and applies a force in the direction opposite to the vibration acceleration or the vibration velocity acting on the vehicle body To become comprises a hydraulic actuator device for sea urchin operating proposes a rear wheel steering apparatus such as a truck to feature.

[0006]

【Example】

 An embodiment in which the present invention is applied to a truck will be specifically described with reference to the accompanying drawings. First, in the plan view and the side view of the main part of the rear part of the vehicle body including the rear wheels shown in FIGS. 1 and 2, reference numeral 10 is a chassis frame of a vehicle such as a truck, and left and right extending in the longitudinal direction of the vehicle body. It is composed of a pair of side rails 12 and a plurality of cross members 14 extending in the vehicle width direction and having both ends fixed to the left and right side rails 12. Reference numeral 16 is a rear axle housing which supports a rear wheel 18 of a double tire type at both end portions in the vehicle width direction, and 20 is a front end portion of which is pivotally attached to an upper end of the first shackle link 22 by a pin 24 and a rear end It is a main leaf spring whose part is pivotally attached to the lower end of the second shackle link 26 by a pin 28.

The lower end of the first shackle link 22 is pivotally attached to a front shackle bracket 32 by a pin 30, and the bracket 32 is fixed to the side rail 12 of the chassis frame 10. The upper end of the second shackle link 26 is pivotally attached to the rear shackle bracket 36 by a pin 34, and the bracket 36 is fixed to the side rail 12 of the chassis frame 10. Therefore, the sprung load of the vehicle body acts on the front end of the main leaf spring 20 in the suspending direction via the first shackle link 22 while the rear end of the main leaf spring 20 has the second end. Through the shackle link 26, the sprung load acts in such a manner that it is supported under the load. Reference numeral 38 denotes a helper leaf spring which is disposed above the main leaf spring 20 and whose front and rear end portions are slidably contacted with the helper topper 40 mounted on the side rail 12 when the load of the vehicle is equal to or more than a set load. .

Rubber pad members 42 are provided on the upper side surface and the lower side surface of the rear axle housing 16 near both ends in the vehicle width direction. An upper support member 44 is mounted on the upper rubber pad member 42, and a lower rubber pad member 42 is mounted on the lower support member 46. A spacer 48 is interposed between the upper support member 44 and the lower support member 46, and a pair of front and rear U bolts 50 arranged in the front-rear direction intermediate portion of the main leaf spring 20 and the helper leaf spring 38 are attached to the upper and lower parts. Both ends of the rear axle housing 16 are attached to the main leaf spring 20 and the helper leaf spring 38 via the rubber pad members 42 by inserting the support members 44 and 46 of FIG. Be connected.

The rubber pad member 42 is composed of a pair of steel plate backing plates each having a shallow U-shaped cross section, and a shallow U-shaped rubber pad sandwiched between the backing plates and fixed by baking. Has been done. When the U-bolt 50 is tightened as described above, since the spacer 48 having a predetermined length is interposed between the upper and lower support members 44 and 46, the rubber pad receives a preset compression force. It is working. (In the illustrated embodiment, the leaf spring device for suspending the rear wheel is composed of the main leaf spring 20 and the helper leaf spring 38, but the helper leaf spring 38 may be omitted. )

Between the side rails 12 of the chassis frame 10, an upper radius rod 54 having a V-shaped planar shape is disposed along the center line in the vehicle front-rear direction, and the apex portion of the radius rod has a ball joint device 56. (Or a rubber bush type joint device having the same effect), the upper end of the differential casing 58 provided in the central portion of the rear axle housing 16 is pivotally attached, and the free ends of both legs of the rod are respectively ball-shaped. It is pivotally attached to the side rail 12 (or the cross member 14) of the chassis frame 10 via a joint device 60 (or a rubber bush type joint device having the same effect).

As shown in the side view of FIG. 2, a pair of left and right brackets 62 are fixed to the lower side surfaces of the rear axle housing 16 near both ends in the vehicle width direction by welding or the like. One end of a pair of left and right lower radius rods 66 is pivotally mounted via a joint device 64 (or a rubber bush type joint device of the same effect). The other end of each lower radius rod 66 is pivotally attached via a pin 74 to the lower end of an operating lever 72 pivotally supported by a pin 70 on a bracket 68 fixed to the web or side wall of the side rail 12. Further, a piston shaft 78 of a hydraulic cylinder device 76 forming a pair of left and right rear wheel steering actuators is pivotally attached by a pin 80 to the upper end of the operating lever 72, and a cylinder 82 of the hydraulic cylinder device is a pin 82. It is pivotally supported by a bracket 86 fixed to the web or side wall of the side rail 12 by 84.

Further, a pair of left and right brackets 88 are fixed to the rear side surfaces of the rear axle housing 16 near both ends in the vehicle width direction by welding or the like, and the bracket 88 has a ball joint device 90 (or a rubber bush type of the same effect). A cylinder 94 of a hydraulic actuator device 92 is pivotally mounted via a joint device). Further, the piston shaft 98 integral with the piston 96 slidably fitted in the cylinder 94 has a free end thereof mounted on a bracket 100 vertically extending downward from the chassis frame 10 with a ball joint device 102 (or It is pivotally attached via a rubber bush type joint device of the same effect.

As well shown in the schematic plan view of FIG. 3, oil holes 104 extending in the axial direction are formed in the piston shafts 98 of the left and right hydraulic actuator devices 92, and each oil hole 104 is formed. One end of the cylinder is connected to a control valve generally indicated by reference numeral 106, and the other end communicates with a piston front chamber 108 in the cylinder 94, and the front chamber 108 has an accumulator or gas spring filled with high pressure gas. 110 are connected to each.

The control valve 106 controls the flow rate of the hydraulic oil flowing from the supply oil passage 114 side to the discharge oil passage 116 side in proportion to the value of the current supplied to the actuator portion 112, thereby making the hydraulic actuator device 92 The pressure of the hydraulic oil in the piston front chamber 108 is controlled.

Next, in FIG. 3, reference numeral 118 is a steering wheel that steers and steers the front wheels 122 via a steering shaft 120, and 124 is an steering wheel 120 that is installed in the steering shaft 120 to steer and steer the front wheels 122. For example, an optical pulse non-contact type front wheel steering angle sensor that detects θ _f , a vehicle speed sensor 126 that detects a vehicle speed v, 128 is preferably a knuckle or other unsprung member of the front wheel 122 or a front portion of the chassis frame 10. An acceleration sensor, which is mounted and detects the vibration acceleration a in the front-rear direction of the vehicle body, 130 represents the output signal θ _f of the front wheel steering angle sensor 124, the output signal v of the vehicle speed sensor 126 and the output signal a of the acceleration sensor 128. A controller that receives and controls the rear-wheel steering control valve 132 that controls the left and right rear-wheel steering hydraulic cylinder devices 76, 134 respectively. Is a hydraulic pump as a hydraulic source for supplying hydraulic oil to the hydraulic cylinder device 76 and the hydraulic actuator device 92, and 136 is an oil tank.

The operation mode of the controller 130 is as shown in the flowchart of FIG. First, the program is started when the vehicle is turned on, and the output signals of the sensors, that is, the front wheel steering angle sensor 124, the vehicle speed sensor 126, and the acceleration sensor 128 are read in step S ₁ . In step S _2, the front wheel turning angle theta _f is whether the reference is greater than the turning angle theta _o to start the rear wheel steering is determined.

If the steered angle θ _f is greater than the set steered angle θ _o (YES), the program proceeds to step S ₃ and it is determined whether the vehicle speed v is greater than a preset reference speed V _o. It When the vehicle speed v is lower than the reference speed v _{o, the} rear wheel steering is not performed and the program returns to step S ₂ . If the vehicle speed v is higher than the reference speed v _o (YES), the process proceeds to step S ₄ , and the target rear wheel turning angle θ _r is calculated in the controller 130.

Next, in step S ₅ , the target rear wheel turning angle θ _r is converted into a stroke difference d _s between the left and right hydraulic cylinder devices 76 (in the flowchart, for convenience, the power cylinder is noted). The stroke difference d _s is supplied as drive power to the rear wheel steering control valve 132 in step S _6. By the control valve 132, hydraulic oil is supplied from the hydraulic power source 134 to the left and right power cylinders 76, one power cylinder 76 is displaced in one direction by a stroke (S + _ds / 2), and the other power cylinder 76 is stroked. displaced in the _(s-d s / 2) it is only the opposite direction.

The left and right hydraulic cylinder devices for steering the rear wheels, which are respectively in the neutral position when the vehicle is traveling straight, the power cylinders 76, that is, the power cylinders 76 in opposite directions, that is, when one power cylinder extends, the other power cylinder moves. The rear axle housing 16 operates so as to contract, and around the center of the ball joint device 56 at the apex of the upper radius rod 54 having the V-shaped rear axle housing 16 in the same direction as the steering direction of the front wheels 122, for example, 1 to 5 degrees. The steering angle is steered by a small angle θ _r within the range, and the steering stability at high speed traveling is improved.

On the other hand, in parallel with the above-mentioned rear wheel steering routine, a routine of the hydraulic actuator 92 for alleviating an impact generated when a vehicle passes a step or the like and improving riding comfort is executed as follows. That is, in step S _7, the acceleration sensor 12 8 by road step or seam, and the determination is made as to whether or not the detected vibration acceleration a of the vehicle body front-rear direction. When vibration acceleration a is detected (YES) the program proceeds to S _8, the high frequency component of the acceleration a is detected by the band-pass filter.

When the high frequency component of the acceleration a is detected in step S ₈ (YES), the step proceeds to S ₉ and a reverse force proportional to the longitudinal acceleration of the vehicle body is applied to the chassis frame 10. The load F in the front-rear direction to be applied between the chassis frame 10 and the rear axle housing 16 is calculated so as to act.

[0022] In yet step _{S 10,} the load F is, hydraulic fluid pressure _{P a} to leave supplied to the piston front chamber 108 of the hydraulic actuator 92 is calculated. In Step S ₁₁ is followed, the control actuator drive output to realize the hydraulic fluid pressure P _a to 112 of the valve 106 is supplied, right and left hydraulic actuator 92 is actuated simultaneously and in the same direction, the front and rear A directional load F is generated. As a result, while the vehicle is traveling, a force proportional to the longitudinal acceleration of the vehicle body caused by the passage of a step or a seam acts on the vehicle body in a direction opposite to the direction of the acceleration by the pair of hydraulic actuator devices 92. As a result, the impact at the time of passing a step or the like is effectively alleviated not only during straight running but also during steered steering accompanied by steering of the rear wheels, and riding comfort is improved, and There is an advantage that vibration noise is reduced.

The operation of the hydraulic actuator device 92 will be described in more detail. When the vehicle is traveling on a smooth road surface, that is, when the hydraulic actuator device 92 is at rest, the control valve 106 supplies hydraulic oil having a relatively low reference pressure, for example, 50 kg / cm ^{2 to} the piston front chamber 108. On the other hand, the hydraulic oil of the same pressure flows into the rear chamber 136 of the piston 96 through the gap between the inner circumferential surface of the cylinder and the outer circumferential surface of the piston, and the backward force acting on the large pressure receiving area of the front chamber 108 of the piston The forward force based on the hydraulic oil pressure acting on the small pressure receiving area of the rear chamber 136 and the forward force of the spring compressed inside the piston rear chamber are balanced. Next, when vibration acceleration occurs when the front wheels 122 pass over a step or the like on the road surface, the control valve 106 operates to instantaneously increase the vibration acceleration of the hydraulic oil pressure in the piston front chamber 108 as described above. It is controlled to a high pressure (for example, 80 kg / cm ² ) or a low pressure (for example, 30 kg / cm ² ) that causes the load F depending on the direction and size, and by the pressure difference acting on the front and rear pressure receiving surfaces of the piston 96, The above-described shock required for the chassis frame 10 is alleviated. Further, when the rear wheel 18 is steered, of course, one hydraulic actuator device 92 needs to expand and the other hydraulic actuator device 92 contracts. This expansion and contraction causes the accumulator or The hydraulic oil in the gas spring 110 is supplied or a part of the hydraulic oil in the piston front chamber 108 flows into the accumulator or the gas spring 110, so that the operation is smoothly performed, so that the steering of the rear wheel 18 is prevented. There is no need to be.

In the above embodiment, the hydraulic cylinder device 76 for steering the rear wheels and the hydraulic actuator device 92 for improving the riding comfort are controlled by the common controller 130 and the hydraulic oil is supplied from the common hydraulic power source 134. It is configured to be supplied, but of course can be modified so that it is controlled by a separate controller and the hydraulic oil is supplied from a separate hydraulic source.

In the above embodiment, the hydraulic cylinder device 76 for steering the rear wheels is operated based on the vibration acceleration a that acts on the vehicle body when the vehicle passes through a step or a joint on the road surface. It is obvious that the vibration velocity can be adopted instead of the vibration acceleration a. Further, in the above embodiment, the rear wheel steering hydraulic cylinder devices 76 are configured to act on the rear axle housing 16 via the respective lower radial rods 66 (in the conceptual plan view of FIG. 3, the lower radial rods are shown). The hydraulic cylinder device 76 can be directly connected to the rear axle housing 16 as well, although the illustration is omitted because 66 is merely an intermediate member.

[0026]

[Effect of device]

 As described above, the rear wheel steering system according to the present invention includes a chassis frame, a rear axle housing that supports rear wheels at both ends in the vehicle width direction, and one end of the rear axle housing arranged along the longitudinal center line of the vehicle body. Part is pivotally attached to the central portion of the rear axle housing in the vehicle width direction and the other end is pivotally attached to the undercarriage frame, and the vehicle speed is interposed between the undercarriage frame and the rear axle housing. Is above the set speed, the hydraulic cylinder device for steering the rear wheels that steers the rear wheels in response to the steered steering of the front wheels, and the vibration acceleration in the longitudinal direction of the vehicle body that acts when passing a step on the road surface or the like. By receiving the output signals of the device that detects the vibration velocity and the device that detects the vibration acceleration or the vibration velocity, a force that is opposite to the vibration acceleration or the vibration velocity that acts on the vehicle body is applied to the vehicle body. It is equipped with a hydraulic actuator device that operates like this, which can improve the steering stability during high-speed traveling of a truck and the like, and also utilize the hydraulic cylinder device for steering the rear wheels to make steps on the road surface. It is extremely useful in practice because it can effectively mitigate the impact when passing through seams and seams, improve riding comfort and reduce vibration noise.

[Brief description of drawings]

FIG. 1 is a plan view of a rear portion of a vehicle showing an embodiment of the present invention.

FIG. 2 is a side view of a rear portion of the vehicle shown in FIG.

FIG. 3 is a schematic plan view of the entire vehicle shown in FIG.

FIG. 4 is a flowchart showing an operation mode of the controller shown in FIG.

[Explanation of symbols]

10 ... chassis frame, 16 ... rear axle housing,
18 ... Rear wheel, 54 ... Upper radius rod, 76 ... Rear wheel steering hydraulic cylinder device (power cylinder), 92 ... Hydraulic actuator device, 106 and 132 ... Control valve,
122 ... front wheel, 130 ... controller.

Claims (1)

[Scope of utility model registration request] 1. A chassis frame, a rear axle housing that supports rear wheels at both ends in the vehicle width direction, and one end of the rear axle housing is pivotally attached to a center portion of the rear axle housing in the vehicle width direction. And the other end of the upper radius rod pivotally attached to the chassis frame,
A hydraulic cylinder device for rear wheel steering, which is interposed between the chassis frame and the rear axle housing and steers the rear wheels in accordance with steering and steering of the front wheels when the speed of the vehicle is equal to or higher than a set speed, A device that detects vibration acceleration or vibration velocity in the front-rear direction of the vehicle body that acts when passing a step or the like, and a vibration acceleration or vibration velocity that acts on the vehicle body by receiving output signals of the device that detects the vibration acceleration or vibration velocity A rear wheel steering device, such as a truck, comprising a hydraulic actuator device that operates so as to exert a directional force on a vehicle body.